Method of making shoes

ABSTRACT

A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould, removing the plastic moulded upper formation from the mould and uniting the lower marginal portion of the upper formation to a sole.

United States Patent Dicks et al.

[54] METHOD OF MAKING SHOES [72] Inventors: Peter D. J. Dicks,Kitchener, On-

tario; William M. Hill, Ayr, Ontario, both of Canada [73] Assignee: MelHill Technical Developments Limited, Preston, Ontario, Canada [22]Filed: Aug. 31, 1970 [21] Appl. No.: 68,419

52 US. Cl. ..12/l46 c 51 1111.01. ..A43d [58] Field 01 Search ..12/142R, 142 15,142 RS,

[56] References Cited UNITED STATES PATENTS Dicksetal ..12/142EX 15]3,685,071 1451 Aug. 22, 1972 3,101,496 8/1963 Bingham et al. 12/142 E1,206,914 12/1916 Price ..l2/142 E 2,582,298 1/1952 Ushakoif ..12/146 C2,904,838 9/1959 Phillips 12/146 C Primary ExaminerPatrick D. LawsonAtt0rneyFetherstonhaugh & Co.

[5 7 ABSTRACT A method of forming a shoe comprising the steps of formingthe upper formation from a plastic material by electrostatic depositionon a mould, removing the plastic moulded upper formation from the mouldand uniting the lower marginal portion of the upper formation to a sole.

13 Claims, 9 Drawing Figures PATENTEflIIIcza I972 3.685.071

sum 1 BF 3 yM/Q7/1 ATTORN EYS PATENTEDAUG 22 1912 SHEET 2 OF 3 FIGZbINVENTORS PETER D. J. D/CKS BalWLL/AM M. HILL flawa ak ATTORNEYSPATENTED M192 2 I972 SHEET 3 BF 3 I 'E.\ TURS PETER D. J. DICKSATTORNEYS METHOD OF MAKING SHOES This invention relates to themanufacture of shoes. In particular, this invention relates to animproved method of manufacturing shoes wherein the shoe upper is made inone piece and subsequently anchored to a sole.

In the manufacture of shoes, it has become common to make the shoe upperformation from plastic material. The production costs can be reduced bysubstituting plastic material for the traditional leather and theplastic can be given the appearance of high grade leather. A furtheradvantage of the use of plastic material in the formation of the upperis that is it possible to form the sole in an injection moulding processwith the plastic upper located in the mould so as to be bonded thereto.This improved method eliminates the costly stitching operations whichhave long been used in the connecting of the sole of a shoe to the upperwhen using the traditional leather upper. With these new techniques,production of the upper has not been simplified to any great extentsince the practice has been to make an upper from a number of plasticelements having the same general contour as the elements previouslyemployed in making a shoe from leather. These elements are then securedtogether either by stitching or bonding by an adhesive or a heat sealingoperation. In addition, considerable difficulty has been experienced inattempting to securely anchor the upper to an injection moulded sole.Unlike the stitching operation, it is difficult to tell by a visualexamination whether or not the connection of the upper to the sole issatisfactory. The problem has been that the marginal edges of the upperare generally straight and when they are moulded into a sole, they arenot anchored in any way.

An alternative method of production which is commonly used in themanufacture of boots and the like is referred to as the slush mouldingmethod. In this method, plastic in liquid state is poured into a mouldhaving the shape of the footwear to be produced and the surface layer ofthe liquid plastic material is chilled on contact with the mould andsolidifies in the mould. After a predetermined period of time, theunchilled liquid plastic material is poured out of the mould leaving acoating of plastic on the surface of the mould. The main disadvantage ofthis method is that it is very difficult to obtain an even thickness ofskin throughout the mould. The uneven cooling of the mould causes localthick spots and thin spots in the moulded article.

The present invention overcomes the difficulties of the prior artdescribed above by providing an improved method of manufacturing a shoewherein the upper formation of the shoe is made in one piece from aplastic material by electrostatically depositing the plastic material ina mould. The moulded upper formation is then removed from the mould andunited at the lower marginal portions thereof to a sole. This improvedstructure eliminates the stitching and sewing of the component parts ofthe upper and thereby considerably reduces the labor costs in themanufacturing operation. A further feature of the present invention isthat it is possible to form the marginal edges of the upper formationwith a permanent set so as to be angularly disposed relative to theremaining portions of the upper formation so as to be firmly anchored ina sole formed by an injection moulding process. The electrostaticmoulding process is suitable for forming a moulded upper from a numberof layers of different plastic material so that it is possible to formthe outer layer with a plastic which will readily conform to the surfacepattern of the mould while forming one or more inner layers from aplastic having other physical characteristics or a plastic which is lessexpensive than that used in the formation of the outer surface.

The invention will be more clearly understood after reference to thefollowing detailed specification read in conjunction with the drawingswherein FIG. 1 is a pictorial view of a mould for use in the formationof a shoe upper according to an embodiment of the present invention;

FIG. la is an enlarged detail view of a marginal edge portion of a mouldand shoe upper;

FIGS. 2 and 2a are cross-sectional views diagrammatically illustratingthe mould of FIG. 1 in operable positions for electrostatic moulding;

FIG. 2b is a plan view of the moulding device of FIG. 20;

FIG. 3 is a cross-sectional view of an upper located in an injectionmoulding device for forming the sole; and

FIGS. 4 to 6 are cross-sectional views illustrating alternative methodsof anchoring the upper to a sole.

The mould 10 illustrated in FIG. 1 of the drawings consists of ashoe-shaped moulding portion having a cavity 11 conforming to theexterior shape of the upper which is to be produced in the mould and aflange 16. The mould cavity 1 1 may also be fonned with a desiredsurface pattern and with imitation stitching seams such as illustratedat 14 in FIG. I. The flange 16 extends outwardly from the mould 10serves to assist in locating the mould 10 relative to an electrostaticcoating apparatus. In FIG. 1a, it will be noted that at the edgeconnection between the shoe-shaped portion of the mould and the flange16, there is a short obliquely extending wall portion 18. This wallportion 18 serves to form the marginal edge of the moulded upper at anangle relative to the adjacent portions of the shoe to provide ananchoring marginal edge or lip as will be described hereinafter.

One of the advantages of the electrostatic moulding process is that amould can be made at a much lower cost than a mould for injectionmoulding. To make the mould for a shoe, a shoe is first made in aconventional manner as by stitching the various panels together. A mouldis then made from the shoe in urethane or rubber or the like. The hollowmaster mould is then supported in a jig to retain its shape and filledwith wax or the like. The urethane or rubber mould is then removedleaving a solid plating master. The wax master is then plated by a vapordeposition of nickel about 0.030 to 0.040 inches on the solid master.The wax is then melted to leave the nickel mould with a cavityconforming to the configuration of the outer surface of a shoe upper asshown in FIG. 1 of the drawings. The small obliquely disposed edge 18 isformed in the mould by making minor modifications to the urethane orrubber mould. One of the features of making a mould in the mannerpreviously described is that it is possible to produce a mould whichwill have a surface pattern conforming very closely to the pattern onthe original shoe. As a result, it is possible to pick up the leathergrain pattern in fine detail.

After the mould has been made, it is transferred to an electrostaticmoulding apparatus of a known type such as that described in our US.Pat. No. 3,369,274, dated Feb. 20, 1968. FIG. 2 illustrates adiagrammatic illustration of a mould mounted in a rotating drum such asthat described in our US. Pat. No. 3,369,274. In this apparatus theplastic is applied to the mould by way of spray heads 17. The chargedplastic particles are sprayed onto the surface of the mould cavity toconform to the shape of the cavity. The mould 10 is heated in themoulding apparatus in a conventional manner. The operation may becarried out in one or more stages to provide a laminated upper formationfrom preselected plastic materials. For example, an upper may be madefrom an outer layer of vinyl, an inter mediate layer of vinyl foam andan inner layer of polypropyl fibers, each being applied in successiveelectrostatic moulding operations. Numerous other plastic materials mayalso be used as, for example, polyvinylchloride, polyethylene andelastomers. In addition, material such as cotton and rayon fibers may beapplied to the molten plastic by an electrostatic flocking process.

It will be noted that this method also provides a con venient method ofapplying a flock coating to the interior of the upper. For example, itis possible to flock coat polypropylene fibers onto the surface of thevinyl when the vinyl is at a temperature suitable for receiving andbonding the fibers thereto. It is a characteristic of flock coating thatthe electrostatically charged particles tend to stand on end and,therefore, a deep pile coating can very easily be applied by thismethod. This method of forming a multi-layered and lined upper providesa substantial advantage over any other form of plastic moulding in viewof the fact that it can be carried out in the same mould. A furtherfeature of the electrostatic moulding process is that the thickness ofthe plastic material which is moulded is substantially uniform.

After the upper has been formed, it is cured by heating in the usualmanner and then it is removed from the mould 10. Generally the upper canbe removed very easily by manually gripping an edge and pulling it out.If a mould has not been treated to ensure that plastic does not adhereto the portion overlying the leg opening of the shoe, it may benecessary to cut the opening in the shoe. This could, of course, beeliminated by applying a coating of an insulating material to the areaof the mould overlying the leg opening and thereby ensuring that theelectrostatically charged particles will not be retained by the mould inthis area. After the moulded upper formation is removed from the mould10, it is transferred to an injection mould such as that shown insection in FIG. 3. This mould may be substantially the same as themoulds presently in use for injection moulding of the sole of a shoe andthe embodiment illustrated in FIG. 3 is only meant to be a diagrammaticrepresentation of known moulding apparatus. In this apparatus, the mouldcavity 24 is formed between split moulds 26 and interior mould plate 28.The moulds 26 and plate 28 are designed to provide a clearance forreceiving the upper formation 12 in a close fitting relationship so asto grip the upper formation 12 therebetween with the marginal edgethereof extending downwardly into the mould cavity 24. It will be notedthat the lip 18 of the upper 20 is located substantially centrally ofthe thickness of the mould cavity. In this position, when the mould isfilled by injection moulding, the lip 18 will be anchored within thesole to form a mechanical connection therewith in addition to thewelding which takes place. Normally a vinyl upper will be renderedplastic at about 340 while the urethane or vinyl sole will be injectedat a temperature of about 430 so that there will be substantial weldingbetween the vinyl upper and the injection moulded sole.

In FIGS. 4, 5 and 6 of the drawings, alternative forms of anchoring lipsare illustrated. Each of these forms may be produced in theelectrostatically formed upper by preparing the mould accordingly. Theformation of the marginal edge in any one of the forms illustrated inFIGS. 4 to 6 serves to firmly anchor the upper formation in theinjection moulded sole. While shoe soles have previously been formed byinjection moulding with the upper having a marginal edge located in themould, it has not previously been possible to form the marginal edgewith a permanent set so as to provide a mechanical lock when themoulding has been completed.

FIG. 2a and FIG. 2b illustrate a further feature of the invention. Inthis embodiment the electrostatic coating is applied by an electrostaticfluidized bed 17a and a portion of the mould is screened by a movableslide 30. The slide 30 is carried by a shaft 32 which is slidably drivenby means of a solenoid valve 34 into and out of a position underlyingthe mould cavity. The valve 34 is mounted on a platform which extendsoutwardly from the fluidized bed. This arrangement enables selectedportions of the mould cavity to be screened while others are exposed topermit a localized increase in the thickness of the predeterminedportions of the upper. It will be understood that a similar result maybe achieved by moving the mould from one moulding station to another andscreening certain portions of the subsequent moulds. For example, aneven coating of plastic may be applied to the mould in the firstmoulding station and an additional localized thickness of the same or adifferent material may be applied in the second moulding station byscreening selected areas of the mould. The method wherein the mould isindexed from one station to another is of particular advantage when thelayers of material which are to be applied in the second mouldingoperation are formed from a different material to that in the firstmoulding operation.

These and other modifications of the present invention will be apparentto those skilled in the art without departing from the scope of thisinvention.

What we claim as our invention is:

l. A method of forming a shoe comprising the steps of forming the upperformation from a plastic material by electrostatic deposition on a mouldand thereafter screening a portion of the mould and electrostaticallydepositing additional plastic material on the unscreened portion of thepreformed upper to reinforce the unscreened portions by increasing thethickness thereof, curing said plastic material, removing the plasticmoulded formation from the mould and uniting the lower marginal portionof the upper formation to a sole.

2. A method according to claim 1 wherein said additional plastic isapplied before the plastic of the first formed upper is cured.

3. A method according to claim 1 wherein said additional plastic isapplied after the plastic of the first formed upper is cured.

4. A method of forming a shoe comprising the steps of forming the upperformation from a plastic material by electrostatic deposition of theplastic material on a mould, curing said plastic material, removing theplastic moulded upper formation from the mould, applying a liner to saidupper formation and uniting said upper formation and liner to a sole.

5. A method of forming a plastic shoe upper which has at least two areasin which the wall thickness is different from one another including thesteps of:

a. electrostatically depositing plastic material in a mould formed tothe contour of the upper and curing said plastic material and removingthe moulded upper from the mould, and

. screening at least a portion of said mould during a predeterminedportion of the time during which said plastic material is beingdeposited whereby the thickness of plastic material deposited on thescreened portion is less than that deposited on the unscreened portion.

6. A method of forming a plastic shoe upper as claimed in claim 5wherein said screening takes place after a substantially uniform coatingof plastic material has been applied to the mould.

7. A method as claimed in claim 6 wherein said additional plasticmaterial is applied before the plastic of a first formed upper portionis cured.

8. A method according to claim 6 wherein said additional plasticmaterial is applied after the plastic of the first formed upper iscured.

9. A method of forming a shoe which has an upper and a sole portion andwherein the upper portion has at least two areas in which the wallthickness is different from one another including the steps of:

a. electrostatically depositing plastic material in a mould formed tothe contour of the upper and curing said plastic material and removingthe moulded upper from the mould,

b. screening at least a portion of said mould during a predeterminedportion of the time during which plastic material is being deposited,whereby the thickness of plastic material deposited on the screenedportions of the mould is less than that deposited on the unscreenedportions of the mould, and

c. uniting the lower marginal portion of the upper formation to a sole.

10. A method of forming a shoe which consists of an upper portion and asole and wherein the upper portion has a toecap portion of a greaterthickness than the remainder of the upper, including the steps of:

a. electrostatically depositing plastic material in a mould formed tothe contour of the upper and curing the plastic material while removingthe moulded upper from the mould,

. screening all but the toecap forming portion of the mould during apredetermined portion of the time during which the plastic material isbeing deposited whereby the thickness of plastic material deposited inthe toecap forming portion of the mould is greater than that depositedin the remainder of the mould whereby the toecap portionof the mould isreinforced, and c. uniting the lower marginal portion of the upper to asole.

11. A method of forming a shoe upper comprising the steps of, forming aunitary shoe upper having a free marginal edge at the lower end thereofby electrostatic deposition of plastic material on a mould having anopen cavity formed to the required contour of the upper, applying aliner by means of an electrostatic flock coating process to the uncuredplastic material, curing said plastic material and removing the curedupper from the mould.

12. A method of forming a shoe comprising the steps of forming a unitaryshoe upper having a free marginal edge at the lower end thereof byelectrostatic deposition of plastic material on a mould having an opencavity formed to the required controu of the upper, applying a liner bymeans of an electrostatic flock coating process to the uncured plasticmaterial, curing said plastic material, removing the cured upper fromthe mould and uniting the cured upper to a sole.

13. A method of forming a shoe as claimed in claim 1 including the stepof applying a liner to the uncured plastic material by means of anelectrostatic flock coating process.

1. A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition on a mould and thereafter screening a portion of the mould and electrostatically depositing additional plastic material on the unscreened portion of the preformed upper to reinforce the unscreened portions by increasing the thickness thereof, curing said plastic material, removing the plastic moulded formation from the mould and uniting the lower marginal portion of the upper formation to a sole.
 2. A method according to claim 1 wherein said additional plastic is applied before the plastic of the first formed upper is cured.
 3. A method according to claim 1 wherein said additional plastic is applied after the plastic of the first formed upper is cured.
 4. A method of forming a shoe comprising the steps of forming the upper formation from a plastic material by electrostatic deposition of the plastic material on a mould, curing said plastic material, removing the plastic moulded upper formation from the mould, applying a liner to said upper formation and uniting said upper formation and liner to a sole.
 5. A method of forming a plastic shoe upper which has at least two areas in which the wall thickness is different from one another including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould, and b. screening at least a portion of said mould during a predetermined portion of the time during which said plastic material is being deposited whereby the thickness of plastic material deposited on the screened portion is less than that deposited on the unscreened portion.
 6. A method of forming a plastic shoe upper as claimed in claim 5 wherein said screening takes place after a substantially uniform coating of plastic material has been applied to the mould.
 7. A method as claimed in claim 6 wherein said additional plastic material is applied before the plastic of a first formed upper portion is cured.
 8. A method according to claim 6 wherein said additional plastic material is applied after the plastic of the first formed upper is cured.
 9. A method of forming a shoe which has an upper and a sole portion and wherein the upper portion has at least two areas in which the wall thickness is different from one another including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing said plastic material and removing the moulded upper from the mould, b. screening at least a portion of said mould during a predetermined portion of the time during which plastic material is being deposited, whereby the thickness of plastic material deposited on the screened portions of the mould is less than that deposited on the unscreened portions of the mould, and c. uniting the lower marginal portion of the upper formation to a sole.
 10. A method of forming a shoe which consists of an upper portion and a sole and wherein the upper portion has a toecap portion of a greater thickness than the remainder of the upper, including the steps of: a. electrostatically depositing plastic material in a mould formed to the contour of the upper and curing the plastic material while removing the moulded upper from the mould, b. screening all but the toecap forming portion of the mould during a predetermined portion of the time during which the plastic material is being deposited whereby the thickness of plastic material deposited in the toecap forming portion of the mould is greater than that deposited in the remainder of the mould whereby the toecap portion of the mould is reinforced, and c. uniting the lower marginal portion of the upper to a sole.
 11. A method of forming a shoe upper comprising the steps of, forming a unitary shoe upper having a free marginal edge at the lower end thereof by electrostatic deposition of plastic material on a mould having an open cavity formed to the required contour of the upper, applying a liner by means of an electrostatic flock coating process to the uncured plastic material, curing said plastic material and removing the cured upper from the mould.
 12. A method of forming a shoe comprising the steps of forming a unitary shoe upper having a free marginal edge at the lower end thereof by electrostatic deposition of plastic material on a mould having an open cavity formed to the required contour of the upper, applying a liner by means of an electrostatic flock coating process to the uncured plastic material, curing said plastic material, removing the cured upper from the mould and uniting the cured upper to a sole.
 13. A method of forming a shoe as claimed in claim 1 including the step of applying a liner to the uncured plastic material by means of an electrostatic flock coating process. 